(19)
(11) EP 2 418 306 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
04.12.2013 Bulletin 2013/49

(43) Date of publication A2:
15.02.2012 Bulletin 2012/07

(21) Application number: 11188429.2

(22) Date of filing: 06.04.2005
(51) International Patent Classification (IPC): 
C30B 29/20(2006.01)
 C30B 15/34(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR LV MK YU

(30) Priority: 08.04.2004 US 820468

(62) Application number of the earlier application in accordance with Art. 76 EPC:
05735710.5 / 1733078

(71) Applicant: Saint-Gobain Ceramics and Plastics, Inc.
Worcester, MA 01615-0138 (US)

(72) Inventors:
  • Locher, John Walter
    Amherst, NH 03031 (US)
  • Zanella, Steven Anthony
    Dublin, NH 03444 (US)
  • Maclean, Ralph Lampson, Jr.
    Manchester, NH 03102 (US)
  • Bates, Herbert Ellsworth
    Milford, NH 03055 (US)

(74) Representative: Zimmermann & Partner 
Postfach 330 920
80069 München
80069 München (DE)

   


(54) Method for forming a single crystal


(57) Various single crystals are disclosed including sapphire. The single crystals have desirable geometric properties, including a width not less than about 15 cm and the thickness is not less than about 0.5 cm. The single crystal may also have other features, such as a maximum thickness variation, and as-formed crystals may have a generally symmetrical neck portion, particularly related to the transition from the neck to the main body of the crystal. Methods for forming such crystals and an apparatus for carrying out the methods are disclosed as well. Particularly described is a method of forming a single crystal, comprising, providing a melt; drawing a single crystal from the die; and pulling the signal crystal upward from the die and into an afterheater, the afterheater having a lower compartment and an upper compartment separated from each other by an isolation structure.







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